Electrical switch

ABSTRACT

The invention relates to an electrical switch with a housing ( 2 ). In the housing ( 2 ) there is a contact system ( 3 ), to which a switching effect can be applied by means of an actuating member ( 6 ) which is arranged in an opening ( 5 ) on the housing ( 2 ) and partly protrudes out of the housing ( 2 ). The part of the actuating member ( 6 ) protruding out of the housing ( 2 ) as well as the opening ( 5 ) in the housing ( 2 ) is covered by a cap ( 9 ) allowing the movement of the actuating member ( 6 ). The cap ( 9 ) has a cover of a hard material and a sleeve-like part ( 11 ) of a flexible material, designed in the manner of a bellows. The cover, designed essentially in the manner of a planar surface ( 10 ), is arranged on the part of the actuating member ( 6 ) protruding out of the opening ( 5 ) in such a way that the actuating member ( 6 ) can be moved via a side of the cover facing the user. One end of the sleeve-like part ( 11 ) is fastened along a peripheral edge on the side of the planar surface ( 10 ) of the cover facing away from the user. The other end of the sleeve-like part ( 11 ) protrudes laterally beyond the surface ( 10 ) of the cover, the protruding other end of the sleeve-like part ( 11 ) being arranged on a region ( 12 ) of the housing ( 2 ) surrounding the opening ( 5 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an electrical switch.

2. Discussion of the Related Art

In electrical equipment used in aggressive operating conditions,precautions have to be taken to protect the electrical switch againstharmful influences which impair its functional capability. Such harmfulinfluences may be, for example, moisture, dust or the like.

Such switches have a housing in which the contact system is located, andan actuating member which is arranged in an opening on the housing,partly protrudes out of the housing and is provided for acting on thecontact system with a switching effect. For protecting the switchagainst harmful influences, arranged on the switch is a cap of elasticmaterial, which covers the part of the actuating member protruding outof the housing as well as the opening in the housing. On account of itselasticity, the cap allows the movement of the actuating member forswitching the contact system.

A disadvantage of the known cap for protecting the switch againstcontaminants is that, when the switch is actuated, a relative movementtakes place between the cap and the actuating member. As a result,destruction of the cap may occur after a certain period of use, inparticular the friction between the cap and the actuating member maylead to cracks in the cap, so that the cap can no longer perform itsprotective function. Furthermore, it is disadvantageous that, on accountof the elasticity of the cap, it is only possible with difficulty toascertain visually which switching state the actuating member assumes.

DE 196 46 474 A1 further discloses an electrical switch with a cap whichhas a cover of a hard material and a sleeve-like part of a flexiblematerial, designed in the manner of a bellows. The cover of the cap isof a pot-shaped design on the side facing away from the user and isarranged on the part of the actuating member protruding out of theopening in such a way that the sleeve-like part is covered by the cover.The actuating member can be moved via the side of the cover facing theuser, for switching the contact system. This design of the cap requiresthat the switch is of a large overall form. Moreover, there is the riskof contaminants accumulating in the pot-shaped part of the cover andpenetrating into the housing of the switch.

SUMMARY OF THE INVENTION

The invention is based on the object of further developing theelectrical switch in such a way that the protection against ingress ofcontaminants into the switch is improved. Furthermore, a small switch ofthis type is to be provided.

A rigid plastic is expediently chosen as the material for the planarsurface of the cover and a flexible plastic, such as a thermoplasticelastomer, is expediently chosen for the sleeve-like part. It is thenappropriate to mold one end of the sleeve-like part on the planarsurface of the cover for fastening in the manner of a two-componentpart. As a result, the risk of contaminants penetrating between thecover and the sleeve-like part at the particularly stressed fasteninglocation is very low.

The planar surface of the cover may be fastened on the actuating memberon the side facing away from the user by means of catch and/or snapelements. As a result, simple mounting is made possible merely byfitting the cap on, with the advantage that impairment of the protectivefunction of the cap is not to be feared. The other end of thesleeve-like part, facing the housing, may be designed such that it canbe slipped over a flange face of the housing in a simple manner or elsebe fitted on by means of a frame-like base.

For additionally improving the sealing of the mounting opening of anitem of equipment in which the switch is fitted, a sealing lip may bearranged at the other end of the sleeve-like part or on the frame-likebase. Furthermore, it is also possible to fit the switch into themounting opening in such a way that part of the sleeve-like part on thecap at the same time seals the mounting opening into the interior of theequipment. As a result, the ingress of contaminants into the equipmentis prevented in a simple manner merely by use of the switch, withoutadditional sealing means for the equipment being necessary.

The switch according to the invention can also be designed in a simpleway such that it can be illuminated, though the protection againstingress of contaminants is completely retained. For this purpose, it issufficient to produce the planar surface of the cover from a plasticwhich is at least partly transparent to light in the visible spectralrange. The lighting means may be arranged in a chamber of the actuatingmember, the chamber being covered by the planar surface of the cover. Toincrease the light yield in the case of a switch which can beilluminated in such a way, it is then also appropriate to produce thesleeve-like part from a plastic which is essentially opaque to light inthe visible spectral range.

The advantages achieved by the invention consist in particular in thatimproved protection against ingress of contaminants into the interior ofthe housing of the switch, which may lead to impairments of the contactsystem located in the housing, is achieved. The risk of the cap beingdamaged during the period of use of the switch is greatly reduced by thehard planar surface of the cover of the cap, serving as an actuatingsurface. In addition, simultaneous protection of the electricalequipment, in the wall of which the switch can be fitted in a mountingopening, against ingress of contaminants through the mounting openingcan also be achieved. Furthermore, the improvement in the protection forthe switch also has the effect of considerably improving its servicelife.

In comparison with the previously used elastic caps, in which therespective switching position of the actuating member can be visuallyascertained only with great difficulty, in the case of the switchaccording to the invention the switching position assumed by theactuating member can be easily seen. In the case of an illuminatedswitch, the light of the illumination is attenuated to a lesser extentthan is the case with the previous elastic caps.

On account of the hard planar surface of the cover of the cap, servingas the actuating surface, the switch according to the invention can beactuated better by the user. The actuating feeling corresponds to thatof a switch with which the user acts directly on the actuating member,whereby the undefinable actuating feeling in the case of a switch withthe conventional elastic cap does not occur. Furthermore, an attenuationof the switching noises produced when actuating the actuating member isbrought about, so that the ergonomics for the user are improved in thecase of the switch according to the invention.

In spite of the sealing against contaminants, the switch according tothe invention can be of a smaller design than a previous protectedswitch. Finally, the user can easily see that the switch is protectedagainst ingress of contaminants, even if the switch is fitted into thewall of an electrical item of equipment. Nevertheless, the esthetics forthe switch are improved in comparison with the conventional protectivecaps.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are described in more detailbelow and are represented in the drawings, in which:

FIG. 1 shows a longitudinal section through an electrical switch,

FIG. 2 shows a section along the line 2—2 from FIG. 1,

FIG. 3 shows a longitudinal section through an electrical switchaccording to a further embodiment,

FIG. 4 shows a section along the figure line 4—4 from FIG. 3,

FIG. 5 shows the electrical switch designed in a way corresponding tothe embodiment according to FIG. 1 and mounted in an item of electricalequipment, and

FIGS. 6 to 12 show various further embodiments for the mounting of theswitch in an item of electrical equipment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, an electrical switch 1 with a housing 2 can be seen. In thehousing 2 there is a contact system 3, to which electrical terminals 4protruding from the housing 2 lead on the underside. On the upper sideof the housing 2 there is an opening 5, in which an actuating member 6protruding partly out of the housing 2 is movably arranged. By means ofthe actuating member 6, which the user actuates manually, a switchingaction on the contact system 3 is made possible.

As seen from FIG. 1, the present case concerns a rocker switch, theactuating member 6 of which is designed as a rocker. In particular, therocker switch can be illuminated, for which purpose a lighting element 7is arranged in a chamber 8 of the rocker. An unilluminated rocker switchis shown in FIG. 3. The switch may also be designed as a pressure switchwith an actuating member or the like designed as a plunger.

To prevent ingress of contaminants, such as water, dust or the like,into the interior of the housing 2, a cap 9 is arranged on the upperside of the housing 2. The cap 9 covers the part of the actuating member6 protruding out of the housing 2 as well as the opening 5 in thehousing 2. Furthermore, the cap 9 is designed in such a way that itallows the movement of the actuating member 6 for switching the contactsystem 3.

As FIGS. 1 and 2 reveal, the cap 9 has a flat cover, which is designedessentially in the manner of a planar surface 10, as well as asleeve-like part 11. The planar surface 10 of the cover and also thehousing 2 consist of a hard material. A rigid plastic, for examplepolycarbonate, is suitable as the material. The planar surface 10 may beof a rectangular, square, circular, oval or similar shape. If the switch1 can be illuminated, at least part of the planar surface 10 of thecover is designed such that it is at least partly transparent to lightin the visible spectral range. The sleeve-like part 11 is designed inthe manner of a bellows and consists of a flexible material. An elasticplastic, for example a thermoplastic elastomer, is suitable as thematerial. If appropriate, the sleeve-like part 11 may also consist ofrubber or the like. The sleeve-like part 11 is fastened by its one endalong a peripheral edge on the side of the planar surface 10 of thecover facing away from the user. The other end of the sleeve-like part11 protrudes laterally beyond the surface 10 of the cover. Thisprotruding other end of the sleeve-like part 11 is arranged on a region12 of the housing 2 surrounding the opening 5.

The planar surface 10 of the cover is arranged on the part of theactuating member 6 protruding out of the opening 5 in such a way thatthe actuating member 6 can be moved via the side of the planar surface10 of the cover facing the user. Since the planar surface 10 consists ofa hard material, to be precise preferably of a rigid plastic, the userhas the same switching feeling as when the actuating member 6 isactuated directly without a cap 9. On the other hand, on account of thedesign of the sleeve-like part 11 in the manner of a bellows, the cap 9does not prevent the movement of the actuating member 6 duringswitching. Nevertheless, the cap 9 ensures reliable protection againstingress of contaminants at the opening 5 into the interior of thehousing 2.

As FIG. 1 reveals, the planar surface 10 of the cover can be fastened onthe actuating member 6 by means of catch and/or snap hooks 13. The snapand/or catch hooks 13 are located on the side of the planar surface 10facing away from the user and can be designed such that they protrudefrom the planar surface 10. For fastening, the cap 9 is placed over theactuating member 6 and the planar surface 10 is then clipped onto theactuating member 6. It goes without saying that other ways of fasteningthe planar surface 10 on the actuating member 6 are also possible, forexample by means of lugs, detents or latching surfaces. A further way offastening by means of pins 14, which engage with a force closure and/orform fit into corresponding receptacles on the actuating member 6, isalso shown in FIG. 3.

For further fastening of the cap 9 on the housing 2 there is on thehousing 2 a flange face 15, which runs all around along the region 12surrounding the opening 5. In a way corresponding to a first embodiment,shown in FIGS. 1 and 2, the other end of the sleeve-like part 11, facingthe housing 2, is designed as an elastic receptacle 16 corresponding tothe flange face 15. On account of this design, the receptacle 16 can beslipped over the flange face 15 for arranging and fastening thesleeve-like part 11 on the housing 2.

In a second embodiment, which can be seen in more detail in FIGS. 3 and4, the other end of the sleeve-like part 11, facing the housing 2, isfastened on a frame-like base 17 of a hard material, such as a rigidplastic, for example polycarbonate or the like. The frame-like base 17is in turn designed as a receptacle corresponding to the flange face 15,so that, for arranging the sleeve-like part 11 on the housing 2, theframe-like base 17 can be fitted onto the flange face 15. For securefastening of the frame-like base 17 on the housing 2, the base 17 hasdetents 18, which can be seen in FIG. 4 and with the aid of whichclipping of the base 17 onto the flange face 15 is made possible.

In a particularly preferred development, one end of the sleeve-like part11 is molded on the planar surface 10 of the cover, to be precise alongthe peripheral edge on the side of the planar surface 10 facing awayfrom the user, for fastening in the manner of a two-component part. As aresult, secure sealing of the cap 9 is achieved and production of thecap 9 is itself likewise simplified. Equally, in the second embodiment,the other end of the sleeve-like part 11, facing the housing 2, may belikewise molded on the base 17 in the manner of a two-component part.The design as a two-component part is appropriate in particular wheneverthe planar surface 10 and/or the base 17 consists of a hardthermoplastic material and the sleeve-like part 11 consists of athermoplastic elastomer.

The switch 1 may, for example, be arranged in an equipment wall 19 of anelectrical item of equipment, as schematically shown in FIG. 5. For thispurpose, in the equipment wall 19 there is a mounting opening 20, intowhich the switch 1 with its housing 2 can be fitted. It is thenappropriate to use the cap 9 at the same time to seal the mountingopening 20 in such a way that ingress of contaminants into theelectrical equipment is effectively prevented. For this purpose, asealing lip 21 may be additionally provided on the receptacle 16 of thesleeve-like part 11, as can be seen in FIGS. 1 and 2 for the firstembodiment. In the second embodiment, a sealing lip 22 may be located onthe base 17, which FIGS. 3 and 4 reveal in more detail. If the switch 1is fitted together with the cap 9 into the mounting opening 20, thesealing lip 21, 22 comes to bear against the equipment wall 19 with asealing effect, as clearly shown by FIG. 5.

Several ways of configuring the mounting of the switch 1 in theequipment wall 19 can be seen in FIGS. 5 to 12. As likewise revealedthere in more detail, the other end of the sleeve-like part 11 protrudeslaterally beyond the surface 10 of the cover in such a way that thesleeve-like part 11 is not completely concealed by the planar surface 10of the cover, as a result of which the sleeve-like part 11 is at leaststill partly visible to the user even after the switch 1 has been fittedinto the electrical equipment.

In a way corresponding to FIG. 5, the switch 1 is fitted into themounting opening 20 located in the equipment wall 19 in such a way thatthe flange face 15 of the housing 1 bears with a sealing effect againstthe outer side 23 of the equipment wall 19 by means of part of the cap9, to be precise in particular of the receptacle 16 of the sleeve-likepart 11. In the embodiments according to FIGS. 6 to 10, the switch 1 isfitted into the mounting opening 20 in such a way that the flange face15 of the housing 2 is located essentially inside the mounting opening20. According to FIG. 6, the flange face 15 is essentially flush withthe equipment wall 19. According to FIG. 7, the flange face 15 protrudesslightly beyond the outer side 23 of the equipment wall 19. In a waycorresponding to FIGS. 9 and 10, the flange face 15 is arranged slightlyset back with respect to the outer side 23 of the equipment wall 19. InFIG. 8, the equipment wall 19 is configured as a double wall, so thatthe flange face 15 engages in the intermediate space 24 of the equipmentwall 19. Finally, in a way corresponding to FIGS. 11 and 12, the switch1 is fitted into the mounting opening 20 in such a way that the flangeface 15 of the housing 2 bears against the inner side 25 of theequipment wall 19. The latter arrangement is particularly preferred,since the actuating member 6 is then located together with the cap 9essentially flush in the equipment wall 19, which allows particularlyergonomic actuation of the actuating member 6 for the user. Differentlydesigned catch arms on the housing 2 for fastening the switch 1 in themounting opening 20 are also shown in FIGS. 9, 10, 11 and 12.

The invention is not restricted to the exemplary embodiments describedand presented. Rather, it also comprises all developments which can becarried out by a person skilled in the art within the scope of the ideaof the invention. For instance, the invention can be used not only onthe rocker switches described but also, as already mentioned, onpressure switches or the like.

What is claimed is:
 1. An electrical switch comprising: a housing, acontact system located in the housing, an actuating member arranged inan opening on the housing, said actuating member partly protruding outof the housing and acting on the contact system with a switching effect,and a cap which covers the part of the actuating member protruding outof the housing as well as the opening in the housing and allows themovement of the actuating member, the cap having a cover of a hardmaterial and a sleeve-like part of a flexible material, the sleeve-likepart including a bellows, and the cover being arranged on the part ofthe actuating member protruding out of the opening in such a way thatthe actuating member is movable via the cover, wherein the coverincludes a planar surface for engagement by a user and a rear surfaceparallel to the planar surface, in that one end of the sleeve-like partis fastened along a peripheral edge on the rear surface, and the otherend of the sleeve-like part protrudes beyond the surface of the cover,the protruding other end of the sleeve-like part being arranged on aregion of the housing surrounding the opening.
 2. The electrical switchaccording to claim 1, wherein the material for the planar surface of thecover and/or for the housing is a rigid plastic and the material for thesleeve-like part is an elastic plastic.
 3. The electrical switchaccording to claim 2, wherein the rigid plastic is a polycarbonate. 4.The electrical switch according to claim 2, wherein the elastic plasticis a thermoplastic elastomer.
 5. The electrical switch according toclaim 1, wherein one end of the sleeve-like part is molded on the planarsurface of the cover for fastening as a two-component part.
 6. Theelectrical switch according to claim 1, wherein the actuating memberincludes a rocker.
 7. The electrical switch according to claim 1,wherein the planar surface of the cover is fastened on the actuatingmember on the rear surface by means of protruding catch and/or snaphooks, pins, lugs, detents, or latching surfaces.
 8. The electricalswitch according to claim 1, wherein a flange face, which runs allaround along the region surrounding the opening, is arranged on thehousing and the other end of the sleeve-like part, facing the housing,includes an elastic receptacle, corresponding to the flange face, insuch a way that the receptacle is slipped over the flange face forarranging the sleeve-like part on the housing.
 9. The electrical switchaccording to claim 8, wherein a sealing lip is located on the receptacleof the sleeve-like part or on the base for coming to bear against anequipment wall, in which the switch is fitted in a mounting opening. 10.The electrical switch according to claim 8, wherein the switch is fittedinto a mounting opening located on an equipment wall in such a way thatthe flange face of the housing bears with part of the cap against anouter side of the equipment wall.
 11. The electrical switch according toclaim 8, wherein the switch is fitted into a mounting opening located onan equipment wall in such a way that the flange face of the housingbears with part of the cap against an inner side of the equipment wall.12. The electrical switch according to claim 8, wherein the switch isfitted into a mounting opening located on an equipment wall in such away that the flange face of the housing is located with part of the capinside the mounting opening and is essentially flush with the equipmentwall.
 13. The electrical switch according to claim 1, wherein a flangeface, which runs all around along the region surrounding the opening, isarranged on the housing and the other end of the sleeve-like part,facing the housing, is fastened on a frame like base of a hard material,and the frame-like base includes a receptacle, corresponding to theflange face, in such a way that, for arranging the sleeve-part on thehousing, the frame-like base is fitted onto the flange face.
 14. Theelectrical switch according to claim 13, wherein the base consists of arigid plastic, and the other end of the sleeve-like part, facing thehousing, is molded onto the base as a two-component part.
 15. Theelectrical switch according to claim 13, wherein the base has detentsfor clipping onto the flange face.
 16. The electrical switch accordingto claim 1, wherein at least part of the planar surface of the coverconsists of a plastic which is at least partly transparent to light inthe visible spectral range, and a lighting element for illumination islocated in a chamber of the actuating member.
 17. The electrical switchaccording to claim 1, wherein the sleeve-like part consists of a plasticwhich is essentially opaque to light in the visible spectral range.